Muscle weakness following constant load exercise under heat stress has been associated with hyperthermia-induced central fatigue. However, evidence of central fatigue influencing intense self-paced exercise in the heat is lacking. The purpose of this investigation was to evaluate force production capacity and central nervous system drive in skeletal muscle pre- and post-cycle ergometer exercise in hot and cool conditions. Nine trained male cyclists performed a 20-s maximal voluntary isometric contraction (MVC) prior to (control) and following a 40-km time trial in hot (35°C) and cool (20°C) conditions. MVC force production and voluntary activation of the knee extensors was evaluated via percutaneous tetanic stimulation. In the cool condition, rectal temperature increased to 39.0°C and reached 39.8°C in the heat (P<0.01). Following exercise in the hot and cool conditions, peak force declined by ∼90 and ∼99 N, respectively, compared with control (P<0.01). Mean force decreased by 15% (hot) and 14% (cool) (P<0.01 vs. control). Voluntary activation during the post-exercise MVC declined to 93.7% (hot) and 93.9% (cool) (P<0.05 vs. control). The post-exercise decline in voluntary activation represented ∼20% of the decrease in mean force production in both conditions. Therefore, the additional increase in rectal temperature did not exacerbate the loss of force production following self-paced exercise in the heat. The impairment in force production indicates that the fatigue exhibited by the quadriceps is mainly of peripheral origin and a consequence of the prolonged contractile activity associated with exercise. © Springer-Verlag 2010.
CITATION STYLE
Périard, J. D., Cramer, M. N., Chapman, P. G., Caillaud, C., & Thompson, M. W. (2011). Neuromuscular function following prolonged intense self-paced exercise in hot climatic conditions. European Journal of Applied Physiology, 111(8), 1561–1569. https://doi.org/10.1007/s00421-010-1781-3
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